Answer
The airplane needs to fly a horizontal distance of 42,642 feet to be directly over the tree.
Work Step by Step
We can convert the angle to degrees:
$\theta = 13^{\circ}50' = (13+\frac{50}{60})^{\circ} = 13.833^{\circ}$
Let $h$ be the height of the airplane. We can use $h$ and $\theta$ to find the horizontal distance $d$ the airplane must fly:
$\frac{h}{d} = tan(\theta)$
$d = \frac{h}{tan~\theta}$
$d = \frac{10,500~ft}{tan~(13.833^{\circ})}$
$d = 42,642~ft$
The airplane needs to fly a horizontal distance of 42,642 feet to be directly over the tree.